Use at 100 uM/ml. Make a 1000x stock of 100 mg/ml in water.
Use 35 ug/ml for expression, 70 ug/ml for plates and pre-cultures. Make a 35 mg/ml stock in ethanol (it won't dissolve in water).
Use at 30 ug/ml. Make a 30 mg/ml stock in water.
Use at 100 uM/ml. Make a 1000x stock of 100 mg/ml in water.